1. Field of the Invention
The present invention relates to a technology for controlling the idle seek of a plurality of disk drives in a disk array device.
2. Description of the Related Art
In order to prevent minute amounts of dust from being deposited on a particular track, disk drives generally have a function such as idle seek that blows away minute amounts of dust by moving the head at fixed intervals. Normally, when a period of a fixed period or more has elapsed since the end of the previous idle seek operation, a disk drive attempts to start idle seek, and starts idle seek if data access is not being executed at this time. However, if data access is being executed precisely at that point in time, an attempt to start idle seek is made again after the data access has ended.
Japanese Patent Application No. H7-121306 discloses a technology that reduces the overhead of the CPU and extends the life of the disk drive as far as possible by not executing idle seek even in the event of an idle seek request when a power conservation processing state is assumed.
However, when data access with respect to a disk drive is frequently not performed in a disk array device, there are cases where a state in which data access is performed even when the disk drive has attempted idle seek prevails and hence idle seek is not executed for a long period. Further, when a read request with respect to the disk drive is received from the host device during disk-drive idle seek, the disk drive cannot be accessed until the idle seek ends. Hence, there are also problems such as that of an interruption of or delay in the processing of the host device. These problems are particularly prominent in the case of a high-capacity disk drive and a high-load environment.